Heat 1 tablespoon vegetable oil in a large skillet over medium heat.
Place 1 pound skirt steak diced into 1-inch pieces on the skillet in an even layer. Season it with 2 tablespoons taco seasoning. Sauté the steak for 1-2 minutes per side until it’s browned slightly.
Add 1 diced red bell pepper and 1 diced yellow onion, and sauté them with the steak for 5-7 minutes until the steak is cooked through and the vegetables are tender.
Top the steak and vegetables with ¼ cup salsa and toss to thoroughly coat the mixture. Sauté for a few minutes to combine the flavors, then remove the mixture from the heat.
Heat a griddle over medium high heat or you can heat a cast iron skillet.
Place 4 burrito-size flour tortillas on the griddle or skillet. Top each tortilla with a small amount of 1 ½ cups shredded cheddar cheese and 1 ½ cups shredded Monterey Jack cheese, then layer the steak and vegetables on top and add more cheese. Carefully fold each tortilla in half.
Cook until one side of the tortilla is golden brown (1-2 minutes). Flip and then cook until the other side is golden brown as well (1-2 minutes). Watch them closely as they brown quickly.
Remove the quesadillas onto a cutting board. Slice them and they are ready to serve and enjoy!
Notes
Refrigerate the leftovers in an airtight container for up to 5 days. We used skirt steak for this recipe but you can also use flank steak if you prefer.